### Summary Coder's subdomain-based workspace app proxy allowed the same-owner CORS check to be bypassed. When a workspace-name subdomain segment parsed as a UUID, the workspace was resolved by ID without confirming the URL's username matched the real owner, while the CORS middleware trusted the unverified username in the hostname. > **Note:** Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated. ### Impact An authenticated user could craft a subdomain encoding their own workspace UUID and a victim's username. If the victim visited the attacker's URL, the attacker's JavaScript could issue credentialed cross-origin `fetch()` requests to the victim's workspace apps and read the responses, exfiltrating data accessible through those apps. ### Patches The fix validates the subdomain username against the resolved workspace's actual owner and bases the same-owner CORS decision on the authoritative owner identity. The fix was backported to all supported release lines: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### Workarounds None. ### Resources - Fix: #26086, #26085 ### Credits Coder would like to thank Anthropic's Security Team (ANT-2026-22434) for independently disclosing this issue!
### Summary Coder's subdomain-based workspace app proxy allowed the same-owner CORS check to be bypassed. When a workspace-name subdomain segment parsed as a UUID, the workspace was resolved by ID without confirming the URL's username matched the real owner, while the CORS middleware trusted the unverified username in the hostname. > **Note:** Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated. ### Impact An authenticated user could craft a subdomain encoding their own workspace UUID and a victim's username. If the victim visited the attacker's URL, the attacker's JavaScript could issue credentialed cross-origin `fetch()` requests to the victim's workspace apps and read the responses, exfiltrating data accessible through those apps. ### Patches The fix validates the subdomain username against the resolved workspace's actual owner and bases the same-owner CORS decision on the authoritative owner identity. The fix was backported to all supported release lines: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### Workarounds None. ### Resources - Fix: #26086, #26085 ### Credits Coder would like to thank Anthropic's Security Team (ANT-2026-22434) for independently disclosing this issue!
Update github.com/coder/coder/v2 to 2.34.2; github.com/coder/coder/v2 to 2.33.8; github.com/coder/coder/v2 to 2.32.7; github.com/coder/coder/v2 to 2.29.17 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanCoder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing affects github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go). Severity is medium. ### Summary Coder's subdomain-based workspace app proxy allowed the same-owner CORS check to be bypassed. When a workspace-name subdomain segment parsed as a UUID, the workspace was resolved by ID without confirming the URL's username matched the real owner, while the CORS middleware trusted the unverified username in the hostname. > **Note:** Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated. ### Impact An authenticated user could craft a subdomain encoding their own workspace UUID and a victim's username. If the victim visited the attacker's URL, the attacker's JavaScript could issue credentialed cross-origin `fetch()` requests to the victim's workspace apps and read the responses, exfiltrating data accessible through those apps. ### Patches The fix validates the subdomain username against the resolved workspace's actual owner and bases the same-owner CORS decision on the authoritative owner identity. The fix was backported to all supported release lines: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### Workarounds None. ### Resources - Fix: #26086, #26085 ### Credits Coder would like to thank Anthropic's Security Team (ANT-2026-22434) for independently disclosing this issue!
AI coding agents often install or upgrade packages automatically in go. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/coder/coder/v2go | >=2.34.0,<2.34.2 | 2.34.2 |
| github.com/coder/coder/v2go | >=2.33.0,<2.33.8 | 2.33.8 |
| github.com/coder/coder/v2go | >=2.30.0,<2.32.7 | 2.32.7 |
| github.com/coder/coder/v2go | <2.29.17 | 2.29.17 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL GuardUpdate github.com/coder/coder/v2 to 2.34.2; github.com/coder/coder/v2 to 2.33.8; github.com/coder/coder/v2 to 2.32.7; github.com/coder/coder/v2 to 2.29.17 if you use the affected versions. Test the change in a non-production environment first.
Local check
hol-guard supply-chain scanCoder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing affects github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go), github.com/coder/coder/v2 (go). Severity is medium. ### Summary Coder's subdomain-based workspace app proxy allowed the same-owner CORS check to be bypassed. When a workspace-name subdomain segment parsed as a UUID, the workspace was resolved by ID without confirming the URL's username matched the real owner, while the CORS middleware trusted the unverified username in the hostname. > **Note:** Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated. ### Impact An authenticated user could craft a subdomain encoding their own workspace UUID and a victim's username. If the victim visited the attacker's URL, the attacker's JavaScript could issue credentialed cross-origin `fetch()` requests to the victim's workspace apps and read the responses, exfiltrating data accessible through those apps. ### Patches The fix validates the subdomain username against the resolved workspace's actual owner and bases the same-owner CORS decision on the authoritative owner identity. The fix was backported to all supported release lines: | Release line | Patched version | |---|---| | 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) | | 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) | | 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) | | 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) | ### Workarounds None. ### Resources - Fix: #26086, #26085 ### Credits Coder would like to thank Anthropic's Security Team (ANT-2026-22434) for independently disclosing this issue!
AI coding agents often install or upgrade packages automatically in go. A medium vulnerability in a dependency can be pulled into a project through a normal install or update without a human reviewing the change, expanding the blast radius from a single package to every agent workspace that depends on it.
| Package | Affected range | Fixed version |
|---|---|---|
| github.com/coder/coder/v2go | >=2.34.0,<2.34.2 | 2.34.2 |
| github.com/coder/coder/v2go | >=2.33.0,<2.33.8 | 2.33.8 |
| github.com/coder/coder/v2go | >=2.30.0,<2.32.7 | 2.32.7 |
| github.com/coder/coder/v2go | <2.29.17 | 2.29.17 |
Fixed versions are reported by the source feed; confirm compatibility before updating.
Reported by GitHub Security Advisories (ghsa).
HOL Guard can help your team review package activity against supported protection paths.
Explore HOL Guard